The welding process has numerous applications in many industries, including the aerospace, automotive, and consumer-electronics fields. Particularly for electronic products, continued reduction of size via dimensional scaling has placed demands on the welding processes utilized to connect disparate parts together. Of the many welding processes, laser welding is particularly useful in small-scale applications due to the ability to focus the laser light on welding areas less than a millimeter in diameter. In laser welding of a wire to an electrical contact, focused light energy is utilized to rapidly heat the weld zone, melting the wire along with the part of the contact to which the wire is being joined. The light energy intensity is controlled by beam size, voltage, pulse width, and may be utilized in single bursts or in pulses repeated at variably timed intervals. Although a variety of lasers may be used for laser welding, one common type of welding laser is a neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser. A Nd:YAG laser typically requires an inert cover gas such as helium or argon to protect the weld from atmospheric gases (e.g., oxygen) that might reduce the quality of the weld.
Advantageously, since laser light is utilized for joining in a laser-welding process, no current flows through the contact or wire, and there is no impact from electrical current polarity on the weld and no electrical connections to the welded contact. Thus, there is no heat generated in the contact by electrical current flow or resistance thereto. Further, as a laser is accurate and produces an energy pulse of repeatable power and duration, it is readily incorporated into manufacturing processes of practically any scale.
Although the laser welding process is accurate, variability in technician skill and experience may cause variability in products, especially on sub-millimeter-scale weld points. Specific fixtures and automation reduce this variability, but at small scales and in small quantities typical of products under development, the welding process is still manually completed by technicians. Furthermore, because a laser beam is utilized to form the weld, the laser welding process is necessarily limited to joining wires or other materials easily placed within the line-of-sight of the laser beam. In addition, some components to which wires are to be joined via laser welding are easily damaged by the intense laser light utilized in the welding process, which can impact production repeatability and yield. Finally, in typical laser-welding procedures, once a wire is welded to an electrical contact the relative geometry of the wire and the contact is fixed, and force applied to the wire in different directions may result in damage to, or even complete detachment of, the weld. Moreover, in many cases it is necessary to join multiple wires to a single electrical contact having limited surface area.
In view of the foregoing, there is a need for techniques and apparatuses enabling repeatable, small-scale laser welding of wires to electrical contacts.